Clay Minerals in Caliche Deposits of Eastern New Mexico

Relative quantitative estimations of clay minerals in samples from twelve profiles of caliche deposits of eastern New Mexico are presented. These profiles represent: High Plains (6), Sacramento Plain (1), Mescalero Plain (1), and Orchard Park (2) and Blackdom (2) Terraces of the Pecos River. The typical clay mineral association is illite, montmorillonite, kaolinite, and chlorite. Randomly mixed layers of illite and montmorillonite; illite and chlorite; and illite, montmorillonite, and chlorite are present in small amounts. Based on mature profiles, the following conclusions are drawn: (1) illite is the most abundant clay mineral and markedly increases toward the top of the profiles; (2) illite content varies inversely with both kaolinite and montmorillonite; and (3) the variations of kaolinite and montmorillonite are approximately parallel. In half of the samples, kaolinite is slightly more abundant than montmorillonite, and the contrary occurs in the other half. In profiles of deposits with a low degree of calichification, illite again is the most abundant clay mineral, but the other relationships do not apply. By comparing the clay minerals present in caliche profiles with published results for various soil types, analogies with chernozem and desert soil are noted.